The present invention relates to an endotracheal tube used for mechanical ventilation of a hospital patient, by insertion of the tube into the trachea of the patient. In particular, the present invention relates to an endotracheal tube having means for irrigating and/or evacuating contaminated secretions accumulating above the tracheal tube cuff and thereby reducing the risk of such contaminated secretions entering the lungs of the patient.
Endotracheal intubation involves the insertion of a tubular device, known as an endotracheal tube, into the trachea of a patient. The endotracheal tube passes through the trachea and terminates at a position above the carina, anterior to a position between the second and fourth thoracic vertebrate. Gases may then be introduced through the endotracheal tube and into the lungs of the patient.
The primary purposes of endotracheal intubation, are to mechanically ventilate the patient's lungs, when a disease prevents the patient from normal, breathing induced ventilation, or to apply anesthetic gases during surgical intervention. In order to create enough air pressure to accomplish such mechanical ventilation and to prevent escape of gases past the tube, it is necessary to seal the passageway around the endotracheal tube. A seal may be produced by the use of an inflatable cuff formed integrally with and surrounding the endotracheal tube. When the endotracheal tube has been introduced into the patient's trachea, the inflatable cuff will normally be located about 3 to 5 centimeters above the carina and within the tube--like trachea.
The inflatable cuff is then inflated so as to engage the wall of the trachea and thereby seal the trachea and prevent gases being introduced through the tracheal tube from simply backing up around the tube. While treatment of this sort has proved successful for patients having chronic or acute respiratory diseases, there is a constant risk of several complications.
In particular, many patients receiving endotracheal intubation develop pneumonia, resulting from an infection of the lungs, possibly induced by contaminated, pooled secretions entering the trachea and the lungs after bypassing the epiglottis during intubation. The epiglottis normally operates as a valve which selectively closes the entry into the trachea and lungs, to prevent the introduction of secretions and particulate matter. However, when an endotracheal tube is in place, the epiglottis is held in an open position, and secretions which would normally be directed away from the trachea and into the digestive system, instead follow the path of the endotracheal tube and pool above the inflatable cuff of the endotracheal tube.
The greatest risk of such infectious secretions reaching the lungs is upon the cessation of mechanical ventilation. In particular, when the need for endotracheal intubation ends, the inflatable cuff of the endotracheal tube is deflated so that the endotracheal tube may be withdrawn from the patient. The infectious secretions which have pooled above the inflatable cuff are then released and are free to flow into the lungs, where bronchitis or pneumonia may rapidly develop. There is also the risk of the infectious secretions reaching the lungs during the intubation, by aspiration of the secretions past the tracheal tube cuff.
To overcome these risks, it is known in the prior art to combine a single lumen suction tube with an endotracheal tube. The suction tube is joined to the endotracheal tube in a suitable manner, the end of the suction tube terminating at a position above the inflatable cuff. The suction tube provides means for suction or evacuation of any pooled secretions which accumulate in the trachea above the inflatable cuff. However, such prior art devices have the disadvantage that use of a single lumen for the suction tube often causes direct suction to be exerted on the tracheal mucosa which may then result in damage to the mucosa.
U.S. Pat. No. 4,840,173 to Porter III, describes an endotracheal tube having a single lumen suction tube merged thereto. In particular, this patent describes a device wherein the suction tube is laminated to the outside of the ventilation tube, so that the suction tube terminates at a position just above the inflatable cuff. The suction tube includes multiple openings which may be used to evacuate secretions which pool above the inflatable cuff. In addition, the inflatable cuff includes a section immediately adjacent to the end of the suction tube that is less flexible than the rest of the inflatable cuff, to insure that the flexible material of the inflatable cuff is not sucked up against the suction tube openings. The endotracheal tube described in the Porter III patent has the disadvantages noted above, that the single lumen suction tube may exert suction on the tracheal mucosa and thereby cause damage to the mucosa. Further, the Porter III device is of a relatively complex design, requiring difficult processing, resulting in expensive production.